To honor the professional career of Professor Howard A. Bern, a symposium entitled "Evolving Concepts of Chemical Mediation" is to be held in conjunction with the American Society of Zoologist's meeting in San Francisco, California, which is planned for December 27 - 30, 1988. Our objective is to discuss various aspects of chemical mediation, incorporating systems from invertebrates to vertebrates, including organismal, cellular, and molecular endocrinology.